The invention relates to an axial setting device in a housing, especially for actuating a multi-plate coupling whose friction plates are alternately connected in a rotationally fast and axially displaceable way to the one and the other respectively of two parts rotatable relative to one another, which rest against an axially fixed supporting disc and which can be loaded in one embodiment by an axially displaceable pressure disc, comprising a setting disc which is rotatably supported in the housing, which is mounted so as to be axially supported in the housing, which is mounted so as to be axially fixed in the housing and which is rotatingly drivable, a pressure disc which is held in the housing, which is held in a rotationally fast way by anti-rotation means arranged in the housing and which is axially displaceable in the housing, or which can be loaded—in another embodiment—by an axially displaceable setting disc, comprising a setting disc which is rotatably supported in the housing, which is mounted so as to be axially displaceable in the housing and which is rotatingly drivable, a pressure disc which is held in the housing, which is held in a rotationally fast way by anti-rotation means arranged in the housing and which is axially fixed in the housing, ball groove configurations in the surfaces of the setting disc and of the pressure disc, which surfaces face one another, which ball groove configurations extends in the circumferential direction, have oppositely directed gradients and are associated with one another in pairs, so as to jointly accommodate a ball and rotary driving means for the setting disc mounted in the housing.
Setting devices of said type combined with the above-mentioned multi-plate coupling are known in different designs and for different applications.
DE 38 15 225 C2 describes such a device which is integrated into a bevel gear differential drive. The setting disc is directly driven by a conical pinion which engages a bevel gear toothing at the setting disc.
From DE 40 07 506 C1, there is known a device of said type which is used in a manual gearbox. The driving means for the setting disc comprise the same parts as mentioned above, but in addition, they comprise a spur gear reduction drive.
DE 41 06 503 C1 refers to a further development of the latter application. It shows the anti-rotation means for the pressure disc which consist of a tongue-and-groove assembly, with the tongue being connected to the fixed part of the housing and the groove constituting an individual notch at the pressure disc.
EP 0 368 140 B1 describes different applications for setting devices of said type, and inter alia, it can be seen that at its circumference, the setting disc can comprise a worm toothing or helical toothing and setting can be effected by means of a worm driven by a motor and positioned on the motor shaft.
In the case of the devises mentioned first, the driving motor for the setting disc has to be kept under voltage for as long as a positive setting force is to be maintained. This means that the capacity of the motor has to be higher or that the motor requires an additional braking device. The latter device can only be equipped with non-self-inhibiting rotary drive means because the device has to feature as little friction as possible. Irrespective of the latter, in the case of failure involving a voltage brake-down, a reverse motion of the device effected by returning forces is almost impossible due to the high friction in the rotary drive means provided in the form of a worm drive. In a case of failure involving voltage brake-down, a multi-plate coupling closed by rotating the setting disc relative to the pressure disc would be released by the rotary drive means only hesitatingly.